Inkscape can do this:
Import the PNG and select it
go to the menu Path / Trace Bitmap
choose Centerline tracing
You can see that it works by setting a different contour color ("set stroke") and changing the line thickness:
black: original PNG
pink: line with thickness 0.1 mm
blue: line with thickness 2.0 mm
To be honest, I seldom do it this way, ...
So, I searched a bit because this filter looks interesting indeed, and it turns out Gimp has such a filter built-in. Gimp is free, open-source and available for Windows, Mac and Linux.
It is part of the "G'MIC" filter package and called "Polygonize" in the "Artistic" section. I have tried it on Gimp 2.8.22 on Linux. I cannot ...
If you want an open-source single-script solution, take a look at the textdeskew
script by Fred Weinhaus.
If you want to see what the script does: there are a few before-after figures on the page that I've linked to.
There are quite a few command line options, for fine-tuning.
Find it on Fred's ImageMagick Scripts for more, e.g. texctcleaner, also with ...
If you are not looking to convert it to text, just move the handwriting to a different picture, you can use paint.net.
You can use either the magic select tool or the lasso tool. If you use the magic wand tool, just select the background of the recipe card and move the tolerance up until it selects the entire background then press delete. If you use the ...
It depends on what you are trying to do. If you are a digital artist, I can suggest Krita. It's really nice for painting and supports all sorts of pressure sensitive pens but you can just use a mouse or trackpad. I've had a crash or two so I save frequently, but otherwise very well featured. Krita is open source and multi-platform.
If you are using the ...
Spire.Presentation for Java library can be used to convert ppt/pptx to images (for instance, jpg, png, tiff, bmp).
Apart from conversion, the library also supports lots of other manipulations, such as add animations, secure ppt/pptx, add shapes/comments/hyperlinks, create table/chart, add SmartArt graphics and many more. You can explore more about it by ...